Tetrathiafulvalene redox-active

In addition, Bryce and Chesney have developed chiral oxazolines linked to tetrathiafulvalene in order to use these ligands as redox-active ligands. When applied to the test reaction, these ligands gave only low enantioselec-tivities (<21% ee), as shown in Scheme 1.32. 

The combination of a phthalocyanine ring with crown ether moieties and redox-active tetrathiafulvalenes gave compound 117 (Scheme 64) and was described by Zou as a good candidate for a redox-active Na+ sensor [133]. 

Scheme 64 Crown ether phthalocyanine 117 with redox-active tetrathiafulvalene groups...

There is a long standing interest in the chemistry and the properties of cyclic compounds containing sulfur atom in modern material chemistry due to their redox chemistry. In particular, the focus has been on dithiole derivatives, e.g., dithiafulvenes and tetrathiafulvalenes, since the finding of metallic conductivity and low temperature superconductivity in radical cation salts. The quite low oxidation potentials of 1,4-dithiin compounds have been reported, recently [109]. On the other hand, thioketene dimers (2,4-bis(alkyli-dene)-l,3-dithietane) have been known for more than 100 years and synthesized by various methods [110-115]. The structure of these dimer compounds is similar to that of the redox-active sulfur compounds therefore, the potential electronic property of the thioketene dimer moiety is considerably attractive with the aim of application to a new and better -donor. 

Several organofullerene donor-acceptor molecular material hybrid systems have been synthesized via 1,3-dipolar cycloaddition reactions of azomethine ylides, via Bingel cyclopropanation and methanofullerene formation intermediates as well as via cycloaddition reactions, that have already been discussed in previous sections. The majority of such hybrid systems possess always as acceptor unit the fullerene core and as donor moieties porphyrins, tetrathiafulvalenes, ferrocenes, quinones, or electron-rich aromatic compounds that absorb visible light [190-193]. The most active research topic in this particularly technological field relies (i) on the arrangement of several redox-active building blocks in... 

Redox polymer — Redox polymers contain electrostatically and spatially localized redox sites, which can be oxidized or reduced. The redox polymers can be divided into subclasses 1) polymers that contain covalently attached redox sites, either built in the chain or as a pendant group. The redox centers may be organic molecules (e.g., tetrathiafulvalene, tetra-cyanoquinodimethane), organometallic molecules (e.g., - ferrocene), or co or dinative ly attached redox couples (e.g., polymerized metal bipyridine(bpy) complexes) 2) ion-exchange polymeric systems, where the redox-active ions are held by electrostatic binding (e.g., Fe(CN)g- 4- in protonated poly(vinylpiridine) or Ru(bpy)j+/2+ in -> Nafion [i]. 

The incorporation of 1,4-phenylenediamine as part of the crown ether produces redox-active macroscopic ligands. Macroscopic redox aetive ligands containing ferrocene-, tetrathiafulvalene- and quinone derivatives have been prepared and are discussed (2). 

Tetrathiafulvalene-containing systems have also been reported. One such pseudorotaxane represents a redox-active system in which a similar molecular motion can be controlled by two different inputs. Reversible dethreading-rethread-ing cycles involving this product can be performed by either oxidation and consecutive reduction of the linear component or reduction and consecutive oxidation of the electron-accepting cyclophane tetracation. As such, the system corresponds to a further level of sophistication in systems of this type. Formally, the input (elec-trochemical)/output (absorption spectrum) characteristics of this assembly correspond to those of an XNOR logic gate. 

Many other catenane species have been synthesised. These range from further simple [2]-catenanes, other [2]- as well as [3]-catenane species incorporating redox-active tetrathiafulvalene groups, other multi-ring derivatives, through to polymeric species incorporating catenane domains as part of a larger macromole-... 

The tetrathiafulvalene (TTF) unit, which can undergo two reversible oxidations, is one of the most common redox-active groups to be incorporated into a supramolecular sensor over the past few years. The groups of Becher, Salle, and Bryce are prominent in this field, publishing... 

The controlled movement in this system is controlled by the interaction among redox-active units at the redox-active tetrathiafulvalene (TTF) units. In the neutral, unperturbed state, the tetracationic cyclophane units (cyclobis(paraquat-para-phenylene), CBPQ F ) are most stable coordinated to the TTF moieties, due to electron donation and Jt-stacking interactions. However, upon oxidation of the TTF units, the CBPQT " rings become electrostatically repelled, migrating to the... 

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